{"id":"F2006B04676","name":"AD/BELL 412/42 - Main Hydraulic Servo Actuator Rod End Lock Washer","slug":"ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44428,"registerId":"commonwealth-F2006B04676-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 412/42 - Main Hydraulic Servo Actuator Rod End Lock Washer","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n![](image.002.png)  \nBell Helicopter Textron 412 Series Helicopters\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/BELL 412/42 Main Hydraulic Servo Actuator\n\nRod End Lock Washer\n\n  \n9/2001\n\nDM\n\nApplicability: Model 412, 412EP and 412CF helicopters incorporating hydraulic servo actuator, part number 41000470, serial numbers with “HR’ prefix up to and including 10010.\n\nRequirement: 1. Inspect the tab on the rod end locking washer of each hydraulic servo actuator for bending and twisting in accordance with “Accomplishment Instructions”, Paragraph 2.A of Bell Helicopter Textron, Inc Service Bulletin 412-00-105 or 412CF-00-12, as applicable.\n\n2. Replace P/No NAS513-6 lock washer with P/No NAS513K6C locking device in accordance with “Accomplishment Instructions”, Paragraph 2.B of Bell Helicopter Textron, Inc Service Bulletin 412-00-105 or 412CF-00-12, as applicable.\n\nNote: FAA AD 2001-08-04 refers\n\nCompliance: 1. Within 25 flight hours after the effective date of this Airworthiness Directive.\n\n2. Within 100 flight hours after the effective date of this Airworthiness Directive or at next actuator overhaul, whichever occurs first.\n\nThis Airworthiness Directive becomes effective on 25 July 2001.\n\nBackground: This Directive is prompted by reports of damaged main hydraulic actuator rod end lock washers which can result in rod end disengagement from the actuator and potential for loss of control of the main rotor.\n\n![](image.003.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 18 July 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 25 July 2001.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive follows its stated safety purpose in the background: inspect and replace a suspected defective lock washer to prevent rod-end disengagement. The AD limits who must comply (models, P/N, serial range) and prescribes inspection and replacement actions consistent with that safety objective, without expanding obligations beyond correcting the identified unsafe condition."},"complexity_factors":["Narrow applicability: specific helicopter models, actuator P/N 41000470 and serials with 'HR' up to 10010","Two mandated actions: immediate inspection and later mandatory replacement","Procedural dependence: implements Bell Helicopter service bulletin paragraphs 2.A and 2.B for technical steps","Fixed compliance windows: inspection within 25 flight hours; replacement within 100 flight hours or at overhaul","Parts specification: replacement requires a particular part number (NAS513K6C)","Regulatory hook: issued under CAR 1998 subregulation 39.1(1) (delegated CASA authority)"],"plain_english_summary":"This Airworthiness Directive requires operators of Bell 412, 412EP and 412CF helicopters fitted with hydraulic servo actuator P/N 41000470 (serials with “HR” up to 10010) to inspect the rod-end lock washer tab for bending/twisting and to replace P/N NAS513-6 with P/N NAS513K6C in accordance with the Bell service bulletin. Inspections are required within 25 flight hours and replacement within 100 flight hours or at the next actuator overhaul. The action is intended to stop washer damage that could allow rod-end disengagement and loss of main-rotor control."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific mechanical defect in a defined subset of Bell 412 helicopters. It has not expanded beyond its initial safety purpose of preventing rod end disengagement."},"complexity_factors":["Single, specific mechanical component targeted (hydraulic servo actuator rod end lock washer)","Clear, unambiguous applicability criteria (specific part numbers and serial number ranges)","Only two distinct compliance actions required (inspection and replacement)","Straightforward time-based compliance (flight hours, not calendar days)","No nested exceptions, conditional logic, or cross-references to other legislation beyond a single reference to FAA AD 2001-08-04 and Bell service bulletins","Short document (approximately 300 words) with minimal defined terms"],"plain_english_summary":"This Airworthiness Directive orders an urgent inspection and replacement of the lock washer on the main hydraulic servo actuator rod end for certain Bell 412-series helicopters to prevent possible disconnection of the rod and loss of main rotor control.\n\nIt affects Bell 412/412EP/412CF with actuator P/N 41000470 (SNs beginning “HR” through 10010). Operators must inspect immediately and install the improved washer within the short compliance windows due to reports of damaged washers."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer","history":"/api/acts/ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer/history","analysis":"/api/acts/ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer/analysis","conflicts":"/api/acts/ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer/conflicts","importantCases":"/api/acts/ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer/important-cases","documents":"/api/acts/ad-bell-412-42-main-hydraulic-servo-actuator-rod-end-lock-washer/documents"}}